Gas blast circuit breaker



H. THOMMEN GAS BLAST CIRCUIT BREAKER April 29, 1941,

Filed ,Feb. 7. 1940 [9, Res llsfan ce Patented Apr. 29, 1941 UNITED STATES PATENT OFFICE as BLAST CIRCUIT BREAKER Hans Thommen, Baden, Switzerland, assignor to Aktiengesellschaft Brown, Boveri & Cie, Baden,

Switzerland Application February 7, 1940, Serial No. 317,752

, In Germany November 17, 1938 s'cl ims. The invention relates to fiuid blast circuit breakers and to arc extinguishing means therefor.

The invention has particular referenceto a after the switching arc has been extinguished is improved when the escaping air blast is directed toward the auxiliary spark gap. However, it,

has been found that extinguishment of the arc at the spark gap is not equally certain under all switching conditions.

It is an object of the invention to provide means to insure extinguishment of the areat the auxiliary spark gap with equal certainty under all switching conditions.

Another object of the invention is to provide a gas blast circuit breaker with an auxiliary spark gap in series with the main arcing contacts in which one electrode of said spark gap comprises means for throttling the discharge passage through which thev pressure blast escapes. A further object of the invention is to provide a gas blast circuit breaker with arcing contacts and a tubular discharge chamber leading from the arcing contacts in combination with an auxiliary spark gap disposed in said discharge chamber in which the electrode of said spark gap nearest the outlet end of said discharge chamber is formed'as an annular disc which throttles the passage'leading to said outlet end.

Other objects and advantages of the invention will become apparent upon reference to the followingdetailed description of the invention in connection with the accompanying drawing, wherein a preferred constructional example of the invention is shown by way of illustration.

In the drawing, Fig. 1 is a central longitudinal section through a circuit breaker embodying the invention, and Fig. 2 is a plan view of the throttling electrode.

While the 1 drawing shows only the circuit breaker per se, it will be understood that the same is connected in the circuit in series with a disconnect switch or the like by means of which the circuit may be permanently opened after the same is broken and the arc extinguished by the circuit breaker.

Referring more particularly to the drawing, I indicates an arcing chamber which is provided Withan inlet fitting 2 through which fluid, such as air, under pressure is "admitted. The compressed fiuid, from a suitable source of supply, such as a storage receptacle or compressed gas generator, is admitted to the pressure chamber I under control of a valve, not shown, which may be operated manually or by automatic means responsive to an overload condition of the circuit. The chamber I, preferably cylindrical in form, may be made of metal, as shown, and is mounted on an insulator 3. If desired, the chamber could itself be formed of insulating material.

The part 4 forming the upper wall of the chamher I is formed with an axialopening in which is mounted the fixed contact 5 of the circuit breaker, this contact being in the form of an annular nozzle flaring or widening towards the discharge side thereof.

A movable switch contact 6 coaxial with the nozzle contact 5 is mounted on an axially movable post I carried by a piston 8 operating in cylinder 9. The contact 6 is normally resiliently held in engagement with the nozzle contact 5 by a resilient spring Ill acting between the wall I I of the cylinder 9 and the contact 6, which latter is shaped to close the opening through the nozzle contact.

An arc collector contact I2 is mounted in the discharge chamber I3 axially aligned with the contacts 5 and 6 and spaced therefrom in the direction of discharge of the pressure from chamher I. This contact I2 serves also as one electrode of an auxiliary spark gap I4. The other electrode I5 of the spark gap, furthest removed from the arcing contacts 5 and 6, is in the form of an annular disc or inverted apertured cuplike member which acts as a throttle, restricting the passage through the discharge chamber I3. The axial aperture I50, in the annular disc I5 acts as a nozzle through which the pressure blast must pass in traveling from the chamber I to the atmosphere.

A directing baflle ring I6 having an axial opening and tapering walls directed toward the spark gap-I4 is mounted in the discharge chamber I3 for directing the fluid under pressure escaping from the pressure chamber upon opening of the contacts 5 and 6, towardthe central aperture I5a of the disc electrode I5.

The disc electrode I 5 is connected by means of I an integral arm I! and bolt II to one side of the switch protecting resistance l9, which is preferably made of Resorbit" in the form of a cylinder carried on the insulating tube 2|! which forms the discharge chamber ii. The other side of s the resistance I9 is connected by a lead 2| and tact 6 to one side of the disconnect. switch, the

circuit being completed by connecting the other side of the disconnect switch to the other terminal of the circuit.

In the operation of the circuit breaker when the circuit is to be opened, compressed air or other fluid is admitted to the chamber I through .inlet 2 by opening of the control valve, before mentioned. Due to the fact that the orifice of nozzle contact is closed by contact 5, pressure will build up in chamber l and cylinder 9 and move piston 8 to shift the contact 5 away from contact 5 against the force of spring 10. This causes an arc to be drawn between contacts 5 and 6. The fluid pressure control valve being kept open, a blast of air or other fluid under pressure rushes through the orifice of nozzle contact 5 against the arcirom all sides, thereby causing a transfer of the are established between contacts 5 and 6 from the contact 5. to the auxiliary contact l2. With alternating current, the luminous arc is extinguished during the passage of the arc current through zero. If the rise of current across the arcing contacts 9n the next half cycle is not very sharp, re-ignition of the arc will not occur since there has been suflicient time for partial deionization of the gas in the arcing chamber. In such event, the circuit breaking operation is completed by opening the disconnect switch, whereupon the fluid pressure valve can be closed. However, if after extincdisc i5. After extinction of the arc, the disconnect switch is opened and the flow of compressed fluid cut off.

It will readily be seen that means are thus provided for insuring extinction of the arc under all switching conditions.

While a preferred embodiment of the inven tion has been shown and described by way or illustration, it will be appreciated that various modifications of the details of construction may be resorted to without departing from the spirit of the invention within the scope of the appended claims.

I claim:

1. In a fluid blast circuit breaker including an arcing chamber having a nozzle contact and a pressure operated movable contact cooperating therewith, means for introducing fluid under pressure into said arcing chamber, a discharge chamber leading from said nozzle contact, an auxiliary electrode coaxially of said nozzle contact and electrically connected to the same, means for throttling the passage through said discharge chamber comprising a throttling electrode disposed in said discharge chamber and positioned to form a spark gap with said auxiliary electrode, and a protective resistance connee-ted across said throttling electrode and said movable contact.

2. In a fluid blast circuit breaker including an arcing chamber having a nozzle contact and a pressure operated movable contact cooperating therewith, means for introducing fluid under pressure into said arcing chamber, a discharge chamber leading from said nozzle contact, an auxiliary electrode coaxially of said nozzle contact, a throttling electrode disposed in said discharge chamber beyond said auxiliary electrode in the direction of flow of pressure fluid, said throttling electrode having a nozzle aperture for the passage of the escaping fluid under pressure tion of the are as the arc current passes through zero the voltage rise on the next half cycle is very sharp, the spark gap M will come into operation to insert the resistance l9 across the arcing contacts, thus damping the voltage rise and lowering the value of the arc current flowing between the contacts 6, l2 and I5 such that the arc may readily be extinguished. The throttling eflect of annular disc electrode l5 prevents a rapid drop in pressure in the discharge chamber and the "luminous arc across the spark gap l4 between contact [2 and, electrode [5 is cooled on all sides and is rapidly deionized by the air escaping through the central aperture I511 due to the building up of the pressure in the discharge chambcr,;on the pressure side of the and positioned to form a spark gap with said auxiliary electrode, and a protective resistance connected across said throttling electrode and said movable contact.

3. In a fluid blast circuit breaker including an arcing chamber having a nozzle contact and a pressure operated movable contact cooperating therewith, means for introducing fluid under pressure into said arcing chamber, a discharge chamber leading from said nozzle contact, an auxiliary electrode coaxially of said nozzle contact, a throttling electrode disposed in said discharge chamber beyond said auxiliary electrode in the direction of flow of pressure fluid, said throttling electrode comprising an annular disc having a restricted central aperture for the passage of escaping fluid under pressure and positioned to form a spark gap with said auxiliary electrode, and a protective resistance connected across said throttling electrode and said movable contact.

HANS THOMMEN. 

